Conventional magnetic resonance imaging has good sensitivity for detecting breast lesions but its specificity is inadequate. High Spectral and Spatial Resolution (HISS) Magnetic Resonance Imaging (MRI) of water and fat signals may increase both sensitivity and specificity of MRI. HiSS MRI equals or exceeds the spatial resolution of conventional MRI and provides detailed spectra of the water and fat in each voxel. The water and fat lineshapes are analyzed to produce images proportional to water resonance linewidth, peak height, integral, changes following contrast media injection, and other parameters. HiSS MRI images are acquired with clinically acceptable run times using echo-planar spectroscopic methods. NIH-funded work in this laboratory demonstrated quantitatively that contrast, edge delineation, and sensitivity to contrast agents in breast images derived from HiSS data are improved compared to conventional images. We now propose to test the method in a large group of women with focal breast abnormalities in order to evaluate whether HiSS MRI improves diagnostic accuracy when combined with conventional MRI, and to extend the quantitative comparisons between HiSS and conventional MRI. We will test HiSS MRI in women with suspicious microcalcifications that may be associated with ductal carcinoma in situ (DCIS). In clinical practice these patients are referred for biopsy, and the biopsies are frequently negative. As a result there is unnecessary anxiety, discomfort, and cost. In addition, some cancers may be missed because of inadequate sampling on biopsy. We propose to use HiSS MRI to scan the location of the microcalcifications. This is an appropriate target for HiSS MRI in its current form because it is localized and has complex morphology. We will test the hypothesis that: Addition of HiSS to conventional MRI exams in women who may have DClS increases diagnostic accuracy. Women with suspicious breast lesions (n=300) who are scheduled for routine clinical MRI scans prior to biopsy will be recruited for this study. Experimental HiSS MRI scans will be integrated into the conventional MRI protocol. We will determine whether addition of HiSS data to conventional data increases sensitivity and specificity. In addition, HiSS images will be quantitatively compared to conventional images. Biopsy results will serve as the 'gold standard'.